Fabric Manufacturing: Weaving, Knitting & Nonwovens

Making fabric from yarn (or directly from fibres). Learn weaving preparation (warping, sizing, drawing-in), loom motions (shedding, picking, beat-up, let-off, take-up), shuttleless looms (rapier, air-jet, water-jet, projectile), basic weaves (plain, twill, satin) and dobby/jacquard, fabric particulars (EPI, PPI, crimp, GSM, cover factor), weft and warp knitting, stitch density, and nonwovens (spunbond, meltblown, needle-punch) — with Python for GSM, cover factor and loom production.

Fabric structure determines drape, strength, comfort, appearance and cost. Woven fabrics interlace two yarn sets at right angles; knitted fabrics interloop yarns, giving stretch; nonwovens bond fibres directly without yarns.

Designers and engineers specify construction — counts, thread densities, weave and finishing — to hit a target weight (GSM), cover and performance.

An analogy

Weaving is like darning a sock with a needle: threads going over and under crossing threads. Knitting is like crocheting a chain of loops — pull it and loops stretch. Nonwovens are like felt: fibres simply matted and bonded together.

Weaving

Warp yarns run lengthwise, weft yarns across. Preparation: winding, warping (direct/sectional), sizing (starch/PVA coating to protect warp from abrasion), drawing-in through heald wires and reed. Primary loom motions: shedding (lifting warp), picking (inserting weft), beat-up (pushing weft into fell). Secondary: let-off and take-up. Shuttleless looms insert weft by rapier, air jet, water jet or projectile at 500–1500 picks/min.

Weaves and design

Basic weaves:

Knitting

Weft knitting (circular machines for T-shirts: single jersey, rib, interlock; flat machines for sweaters) forms loops across; warp knitting (tricot, raschel) forms loops lengthwise from many warp yarns — for sportswear, lace, nets. Loop length controls GSM, tightness and dimensional stability; fabrics shrink and spirality must be controlled by relaxation and finishing.

Nonwovens and fabric engineering

Nonwovens: web formation (carded, airlaid, wetlaid, spunbond, meltblown) then bonding (needle-punching, hydroentangling, thermal, chemical). Used in masks (meltblown filtration layers), wipes, hygiene products, geotextiles and filters. Fabric engineering relates construction to properties: Peirce's geometry, jamming, tear and tensile strength, air permeability, drape and handle (Kawabata KES-F).

Formulas

Worked example: GSM

Given: 110 × 80, 40s × 40s, crimp 8%/6%

Find: GSM.

Answer: 118.3 g/m²

Worked example: Loom production

Given: 800 ppm, η 90%, 70 PPI

Find: m/h.

Answer: 15.7 m/h

Worked example: Stitch density

Given: 18 cpc, 13 wpc

Find: S.

Answer: 234 loops/cm²

GSM, cover factor and loom production

import math
# Woven fabric: GSM from constructional particulars, cover factor and loom production
epi, ppi = 110, 80                   # ends and picks per inch
warp_Ne, weft_Ne = 40.0, 40.0
crimp_w, crimp_f = 0.08, 0.06
warp_tex, weft_tex = 590.5 / warp_Ne, 590.5 / weft_Ne
gsm = (epi / 0.0254 * warp_tex * (1 + crimp_w) + ppi / 0.0254 * weft_tex * (1 + crimp_f)) / 1000
print(f"fabric weight {gsm:.1f} g/m2")
# Peirce cover factor K = threads/cm * sqrt(tex) / 10
K1 = epi / 2.54 * math.sqrt(warp_tex) / 10
K2 = ppi / 2.54 * math.sqrt(weft_tex) / 10
Kc = K1 + K2 - K1 * K2 / 28
print(f"cover factors warp {K1:.1f}, weft {K2:.1f}, cloth {Kc:.1f} (max 28)")
# Loom production: 600 picks/min, efficiency 88%
rpm, eff = 600, 0.88
m_per_h = rpm * 60 * eff / (ppi / 0.0254)
print(f"loom production {m_per_h:.2f} m/h = {m_per_h*24:.0f} m/day")
# Knitted fabric: stitch length and loop shape
courses_cm, wales_cm = 16, 12
print(f"stitch density {courses_cm*wales_cm} loops/cm2")
# fabric weight 118.3 g/m2
# cover factors warp 16.6, weft 12.1, cloth 21.5 (max 28)
# loom production 10.06 m/h = 241 m/day
# stitch density 192 loops/cm2

A 40s × 40s, 110 × 80 poplin weighs ~118 g/m² — a typical shirting. The cloth cover factor of 21.5 (out of 28 for full cover) shows a fairly close but not jammed structure. An air-jet loom at 600 ppm makes ~240 m/day; more picks per inch means slower production.

Common mistakes

Applications

Key takeaways

Going further